What happened
On June 19, 2007, an Apex DR 400-140 (registration F-HJPS) was conducting an instructional flight departing from Caen. During the flight, the student pilot performed a simulated field landing followed by a go-around. While stabilized at 1,500 feet approximately eight nautical miles north of the airfield, the engine experienced a sudden and significant loss of power, dropping from 70% to 46% according to the engine instruments.
Upon the loss of power, the instructor took control of the aircraft and diverted to the Courseulles microlight airfield, located 1.5 nautical miles away. The aircraft landed safely on the 360-meter runway without further incident or damage to the airframe.
The investigation
The investigation focused on the mechanical failure of the Thielert turbo diesel TAE125-01 engine. Post-flight inspection of the engine revealed that the flexible piping, which connects the air intake cooler to the engine, had become disconnected from the metal outlet tube of the cooler.
Investigators found that the engine manufacturer had recently issued Service Bulletin TM TAE 671-0001 on June 15, 2007, following similar incidents. This bulletin recommended replacing the existing cooler with a new model featuring an extended metal outlet tube and updated hose clamps. The maintenance facility for the aircraft had ordered these replacement parts on June 18, 2007, but the components had not yet arrived at the time of the accident.
Findings
- The primary cause of the power loss was a design flaw in the air intake circuit.
- The flexible intake piping became detached from the air cooler's metal outlet.
- There were no injuries or damage to the aircraft or persons on board.